A sterile implantable hemisphere-shaped device used as part of a partial hip replacement (femoral) and designed to interface with the acetabulum on its outer surface where it freely rotates, and interface with a femoral head prosthesis on its inner surface where it allows free rotation of the head. It is a one-piece device typically composed of an outer metal shell (e.g., titanium alloy) and an inner polyethylene (PE) liner; it is typically used for older femoral fracture patients.